This invention relates to a recuperative heat exchanger that is comprised of independent modules lying in juxtaposition and enclosed in an integral housing. A heating fluid is directed axially through adjacent modules between aligned inlet and outlet ports, while a fluid to be heated is directed over a serpentine flow path between laterally adjacent inlet and outlet ports at a single side of the housing.
Presently used apparatus of this type fixedly connects adjacent modules together into a structurally integral unit. When adjacent modules are connected together and exposed to different temperatures, differential expansion of the several modules forces them to expand away from a fixed connection causing excessive offset of modules and excessive stresses in any connection or expansion joint positioned between each module and the surrounding housing. Moreover, such excessive expansion may cause a cracking of the connection between adjacent modules and excessive leakage therefrom to significantly lower the operating effectiveness of the heat exchanger.